Our Mega Run-About Ball measures 13" in diamater and is the BIGGEST ball available anywhere! Now provide larger pets with the freedom to exercise. Bigger pets can now enjoy the world around them inside these colorful, oversized exercise balls. It???s an excellent source of exercise for pet rats and chinchillas, plus its a fun roly-poly toy for ferrets and a neat pet carrier for guinea pigs. The Mega Run-About Ball also fits perfectly onto Super Pet's Hamtrac Raceway for the safest and most controlled exercise environment. Mega Run About ball is a great way to encourage healthy exercise in a secure and safe way. it makes a great temporary holding area to keep your furry friend inside while you clean their home. It is 13" in diameter, and is ideal for pet rats, guinea pigs, chinchillas or other small animals. It makes a great roly-poly toy for ferrets and a neat pet carrier for guinea pigs.